Method for producing prepolymers containing isocyanate groups and urethane groups

ABSTRACT

The invention relates to a method for producing prepolymers containing isocyanate groups and urethane groups. The inventive method comprises the following steps a) at least one polyisocyanate having a stoichiometric deficit of at least one t compound is reacted with at least two hydrogen atoms reacting with isocyanate groups, and b) the reaction product from step a) is distilled by means of a molecular evaporator.

The invention relates to a process for the preparation of prepolymerscontaining isocyanate and urethane groups, also referred to as NCOprepolymers, and the prepolymers obtainable by this process.

Prepolymers containing urethane groups and terminal isocyanate groupsare important intermediates for the preparation of polyurethanes. Theyhave been known for a long time and are extensively described in theliterature.

Their preparation is carried out by reaction of compounds having atleast two isocyanate-reactive hydrogen atoms with an excess ofpolyisocyanates. This reaction will usually leave unconverted monomer inthe prepolymer. This is regarded as a disadvantage, since it reduces theutility of the prepolymers. For instance, some monomers, such astolylene diisocyanate (TDI) or the aliphatic diisocyanates, have a lowvapor pressure and a high toxicity. And, in the case of the isomers ofdiphenylmethane diisocyanate (MDI), the monomers can crystallize out inthe prepolymer.

A range of measures are known which can reduce the level of monomer inthe prepolymer.

U.S. Pat. No. 6,133,415 describes the demonomerization of prepolymerscontaining isocyanate and urethane groups by liquid-liquid extraction.However, this process is inefficient, and the extracted monomers must beseparated from the extractant.

DE-A-196 16 046 describes a process for the separation of monomers orauxiliaries from organic polymers, in which the monomers are extractedfrom the polymers by means of compressed carbon dioxide. However, thedemonomerization of prepolymers containing isocyanate and urethanegroups, in particular those based on MDI, often results in damage to theproduct, for example discoloration or an increase in the molecularweight. Also, carbon dioxide often remains in the product, which canlead to problems in further processing.

A further possible method of separation of the monomers is distillation.Since prepolymers containing isocyanate and urethane groups are usuallyunstable at high temperatures, the distillation is preferably carriedout with the use of azeotroping agents or preferably at reducedpressure, in particular by means of a thin-film evaporator.

WO 97/46603 describes a process for the removed of monomericdiisocyanates from prepolymers containing isocyanate and urethane groupsby distillation, in which a mixture of organic solvents with differingboiling points is used as an azeotroping agent. However, the use ofazeotroping agents makes the process more expensive, and the monomersmust also be separated from the azeotroping agent before they can beused again.

EP-A-316 738 describes a process for the preparation of TDI-basedprepolymer containing isocyanate and urethane groups that-has a lowmonomer content, in which the prepolymer is subjected to a thin-filmdistillation after its preparation. JP 9053522 describes a process forthe preparation of prepolymers containing, isocyanate and urethanegroups, which are likewise subjected to a thin-film distillation aftertheir preparation. JP 08176252 and JP 08176253 describe prepolymerscontaining isocyanate and urethane groups and having a content ofmonomeric MDI of 0.15% by weight, which are subjected to a vacuumdistillation after their preparation.

U.S. Pat. No. 5,202,001 describes a process for the demonomerization ofprepolymers containing isocyanate and urethane groups, in particularthose based on TDI, by thin-film evaporation in the presence of inertgases. This is said to suppress cleavage of the prepolymer backbone.U.S. Pat. No. 5,115,071 describes various techniques for thedemonomerization of prepolymers containing isocyanate and urethanegroups. In one example, a TDI-based prepolymer containing isocyanate andurethane groups is treated by thin-film distillation.

Particularly in the case of prepolymers prepared on the basis of MDI, inparticular where a high content of the 2,4′-isomer is present, theseparation of the monomers at a conventional thin-film temperaturebecomes difficult because of the high boiling point of MDI.

In extraction processes or distillations with the use of azeotropingagents, the removed monomer is obtained in a mixture with othermaterials and must be separated from these in an additional process stepbefore it can be used again.

It is an object of the present invention to provide a simple and gentleprocess for the demonomerization of prepolymers containing isocyanateand urethane groups, which is particularly suitable for the processingof prepolymers containing isocyanate and urethane groups based on MDI,in particular 2,4′-MDI, and in which the removed monomer is obtained insuch a form that it can be reused without further purification.

We have found that this object is achieved by distillation of theprepolymer containing isocyanate and urethane groups by means of ashort-path evaporator.

The invention therefore provides a process for the preparation ofprepolymers containing isocyanate and urethane groups, comprising thesteps of

-   -   a) reacting at least one polyisocyanate, in particular at least        one diisocyanate, with a less than stoichiometric quantity of at        least one compound having at least two isocyanate-reactive        hydrogen atoms,    -   b) distilling the reaction product from step a) by means of a        short-path evaporator.

The invention further provides a process for demonomerization ofprepolymers containing isocyanate and urethane groups, wherein theprepolymer is subjected to distillation by means of a short-pathevaporator after the reaction.

The invention further provides prepolymers containing isocyanate andurethane groups, in particular based on MDI, obtainable by the processof the invention.

The invention further provides prepolymers containing isocyanate andurethane groups based on MDI having an NCO content in the range from 30to 1% by weight and a content of free MDI of smaller than 0.1% by weightand preferably smaller than 0.05% by weight, based in each case on theweight of the prepolymer.

Short-path evaporators are well known. They are commercially availablefrom, for example, VTA Verfahrenstechnische Anlagen GmbH Deggendorf, QVFEngineering GmbH Leipzig or UCI GmbH Alzenau-Hbrstein. A description ofa short-path evaporator can be found, for example, in the article“Kurzweg-Destillation im Labor” by Norbert Kukla, GTLabor-Fachzeitschrift 6/98, pages 616 to 620.

Short-path evaporators are based on the principle of thin-filmevaporation. In contrast to thin-film evaporators, where the vaporsleaving the liquid are conducted upwardly out of the evaporator and arecondensed in an external condenser, short-path evaporators are fittedwith a centrally mounted internal condenser. The vapors leaving theliquid film arrive at the internal condenser, condense there and run offdownwardly. The large cross-sectional area, which is available for thetransport of the vapors from the evaporator to the internal condenser,as well as the small separation between the evaporation andcondensation, only result in small pressure drops in the evaporator.

In contrast to the thin-film evaporator, in which a vacuum of only 1mbar can be achieved, a vacuum of 0.001 mbar is achievable with ashort-path evaporator.

By the use of a short-path evaporator for the demonomerization ofprepolymers according to the invention, it is possible for the firsttime to prepare prepolymers containing isocyanate and urethane groupsbased on MDI with a content of free MDI of smaller than 0.1% by weight,and preferably smaller than 0.05% by weight in each case based on theweight of the prepolymer.

Therefore, the process of the invention is also preferably used in thepreparation of those prepolymers containing isocyanate and urethanegroups where MDI is the polyisocyanate used in their preparation.Surprisingly, it is possible by means of the process of the invention,to remove substantially all of the MDI from the NCO prepolymer. Throughthe choice of the conditions for the distillation in the short-pathevaporator, it is furthermore possible to carry out the removal of MDIwith high selectivity.

The distillation in the short-path evaporator is preferably carried outat from 10 to 10⁻³ mbar, a temperature in the feed vessel of from 30 to90° C., a temperature in the evaporator of from 50 to 210° C. and atemperature in the condenser of from 15 to 55° C. Under theseconditions, optimal removal of unreacted monomers is ensured, withoutcausing damage, in particular degradation, of the prepolymer. Themonomeric diisocyanate that has been distilled off is similarlyundamaged and can again be converted to prepolymers containingisocyanate and urethane groups without any further purification steps.The industrial process of the process can involve the monomericdiisocyanate that has been distilled off being introduced directly tothe storage tank stock reservoir vessel for the diisocyanate for thepreparation of the prepolymers.

When carrying out the process in a laboratory, a short-path evaporatoris preferably operated at a flow rate of from 1 to 0.1 l/h and a stirrerspeed of from 300 to 500 rpm. Scaling can be carried out by thoseskilled up in the art in the usual way.

In a particularly preferred embodiment of the process according to theinvention, process step b) is carried out in a battery of at least twoevaporators connected in series, of which at least one is a short-pathevaporator. Preference is given to all evaporators of the battery beingshort-path evaporators. Up to 20 evaporators may be connected in series.The use of a larger number of evaporators makes the process moreexpensive without providing improved purification. Preference is givento connecting from 2 to 10 and especially from 2 to 5 evaporators inseries. The use of a battery is especially advantageous when theprepolymers composed of two isocyanates having different evaporationtemperature, for example MDI and TDI are used. Even in the case ofdiisocyanates which have monomer contents that can only be lowered withdifficulty, such as 2,4-MDI, a battery may lead to better purification.

In the evaporators, the same or different pressures and temperatures maybe set.

A further advantage in the use of evaporator batteries is that thetechnical requirements on the vacuum-generating units are lower than inthe case of the use of only one evaporator.

The prepolymers containing isocyanate and urethane groups of theinvention can, as described above, be prepared by reaction ofpolyisocyanates with compounds having at least two isocyanate-reactivehydrogen atoms.

Suitable polyisocyanates include, for example, aliphatic, cycloaliphaticand particularly aromatic diisocyanates. The following are specificallynamed by way of example: aliphatic diisocyanates, such as hexamethylene1,6-diisocyanate, 2-methylpentamethylene 1,5-diisocyanate,2-ethylbutylene 1,4-diisocyanate or mixtures of at least two of saidC6-alkylene diisocyanates, pentamethylene 1,5-diisocyanate and butylene1,4-diisocyanate, cycloaliphatic diisocyanates, such as1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophoronediisocyanate), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and-2,6-cyclohexane diisocyanate, as well as the corresponding isomermixtures, 4,4′-, 2,4′- and 2,2′-dicyclo-hexylmethane diisocyanate, aswell as the corresponding isomer mixtures and preferably aromaticdiisocyanates, such as 1,5-naphthylene diisocyanate (1,5-NDI), 2,4- and2,6-tolylene diisocyanate (TDI) as well as their mixtures, 2,4′-, 2,2′-,and preferably 4,4′-diphenylmethane diisocyanate (MDI) as well asmixtures of at least two of these isomers, polyphenylpoly-methylenepolyisocyanate (polymeric MDI, PMDI) having two or more aromaticsystems, mixtures of 2,4′-, 2,2′- and 4,4′-diphenyl-methanediisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI),mixtures of crude MDI and tolylene diisocyanates, polyphenylpolyisocyanates, urethane-modified liquid 4,4′- and/or2,4′-diphenylmethane diisocyanate and 4,4′-diisocyanatodiphenyl-ethane(1,2). Suitable isocyanate components can also include derivatives ofsaid isocyanates, such as uretdione, urea, biuret or isocyanurate andmixtures thereof.

As described above, the process of the invention works particularly wellwhen employed for making and demonomerizing these prepolymers containingisocyanate and urethane groups where the polyisocyanate is MDI,preferably 4,4′-MDI, 2,4′-MDI and mixtures thereof.

The use of 2,4′-MDI is particularly advantageous, because prepolymersprepared from it usually have a lower viscosity than those prepared from4,4′-MDI, and can therefore be further processed more easily to givepolyurethanes. Such prepolymers are particularly useful as adhesives,sealing compositions and sealants. A particular advantage of theprepolymers based on 2,4′-MDI of the invention is their relatively lowviscosity. For this reason, they are easier to handle during furtherprocessing and have a higher storage stability than those based on4,4′-MDI.

Suitable compounds having at least two isocyanate-reactive hydrogenatoms preferably have at least two hydroxyl and/or amino groups in themolecule. Particularly suitable compounds have a molecular weight Mn inthe range from 60 to 10 000 g/mol. The compounds having at least twoisocyanate-reactive hydrogen atoms are particularly preferably selectedfrom the group consisting of polyfunctional alcohols, polyetheralcohols,polyesteralcohols, polyetherpolyamines, hydroxyl-containingpolycarbonates, hydroxyl-containing polyacetals and any mixtures of atleast two thereof. Polyfunctional alcohols and polyether-alcohols, aswell as mixtures thereof, are particularly preferred.

Examples of suitable polyfunctional alcohols are alkanediols having from2 to 10, preferably from 2 to 6 carbon atoms, as well as higheralcohols, such as glycerol, trimethylolpropane or pentaerythritol.Furthermore, natural polyols can be used, such as castor oil.

The polyetheralcohols are preferably from di- to octafunctional. Theirpreparation is usually carried out by addition of alkylene oxides, inparticular ethylene oxide and/or propylene oxide, to H-functionalstarters. The alkylene oxides can be used individually, in sequence oras a mixture. Possible starters include, for example, water, diols,triols, alcohols of higher functionality, sugar alcohols, aliphatic oraromatic amines or aminoalcohols.

Polyetheralcohols having an average molecular weight in the range from500 to 3 000 g/mol and an average OH-functionality in the range from 2to 3 are particularly suitable. Particularly preferred starters for thepreparation of these polyetheralcohols are propylene glycol andglycerol. Preferred alkylene oxides are ethylene oxide and propyleneoxide.

Polyesteralcohols having average molecular weights in the range from 1000 to 3 000 g/mol and an average OH-functionality in the range from 2to 2.6 are also preferred. Polyesteralcohols-based on adipic acid areparticularly preferred. The preparation of the prepolymers is carriedout, as explained, by reaction of the polyisocyanates with the compoundshaving at least two isocyanate-reactive hydrogen atoms.

Suitable catalysts, which in particular speed the reaction between theNCO groups of the diisocyanates and the hydroxyl groups of thepolyalcohols, include the known and conventional strongly basic aminesand also organic metal compounds such as titanic esters, iron compoundssuch as iron(III) acetylacetonate, tin compounds, e.g. tin(II) salts oforganic carboxylic acids, or the dialkyltin(IV) salts of organiccarboxylic acids or mixtures of at least two of the named catalysts, aswell as synergistic combinations of strongly basic amines and organicmetal compounds. The catalysts can be used in the usual quantities, forexample from 0.002 to 5% by weight, based on the polyalcohols.

The reaction can be carried out continuously or batchwise in the usualreactors, for example the known tubular or stirred-tank reactors,preferably in the presence of the usual catalysts, which speed thereaction of the OH-functional compounds with isocyanate groups, with orwithout inert solvents, i.e. compounds that do not react with theisocyanates and OH-functional compounds.

It has been determined that, surprisingly, prepolymers based on 2,4′-MDIhave a considerably lower product viscosity than analogous prepolymersbased on 4,4′-MDI. Viscosity differences of up to 50% were found.

For instance, an NCO prepolymer which was prepared using apolyetheralcohol having a molecular weight of 1 965 g/mol based onpropylene glycol and propylene oxide having an NCO content of 5.5% byweight gave a viscosity of 6 366 mP·s at 25° C. from 2,4′-MDI and aviscosity of 10 261 mPa·s from 4,4′-MDI.

An NCO prepolymer which was prepared by using a polyetheralcohol havinga molecular weight of 1 965 g/mol based on propylene glycol andpropylene oxide (polyol 1) having an NCO content of 4.3% by weight gavea viscosity of 4 283 mP·s at 25° C. from 2,4′-MDI and a viscosity of 12793 mP·s at 25° C. from 4,4′-MDI.

The subject prepolymers containing isocyanate and urethane groups arecustomarily used in the preparation of polyurethanes. To this end, theprepolymers containing isocyanate and urethane groups are reacted withcompounds that can react with isocyanate groups. The compounds that canreact with isocyanate groups include, for example, water, alcohols,amines or compounds having mercapto groups. The polyurethanes can beused as foaming agents, coatings, adhesives, in particular melt-appliedadhesives, paints, as well as compact or cellular elastomers. Where theyare used as sealants or adhesives, the curing to give finishedpolyurethanes is carried out in the simplest case by the action of themoisture in air.

The prepolymers of the invention may be useful for the preparation ofpolyurethane films, in particular those for the food sector. It is notonly for that but also for use as melt-applied adhesives, in particularhot-melt adhesives, coatings or seals that prepolymers based on 2,4′-MDIare particularly suitable.

The invention is illustrated by the following examples.

Investigations were carried out on prepolymers containing isocyanate andurethane groups based on methylene di(phenyl isocyanate) or tolylenediisocyanate. The prepolymers were synthesized by known methods at 80°C. in an experimental apparatus, which consisted of a heatable glassreactor equipped with stirrer, temperature gage, reflux condenser, inertgas inlet (nitrogen) and external heating (table 1). TABLE 1 Prepolymer1 Prepolymer 2 Prepolymer 3 Composition 4,4′-MDI 2,4′-MDI Lupranat ®Polyol 1 Polyol 1 T 80 A*) Polyol 1 NCO content 5.5 5.2 6.3 [% byweight] Viscosity at 10 261      6 400     2 560     25_C. [mPaVs]Diisocyanate 7.6 6.8 6.5 monomer content [% by weight]**)*)Lupranat ® T 80 A (BASF; 80% of 2,4′-tolylene diisocyanate and 20% of2,6′-tolylene diisocyanate)**)determined by HPLC

To remove the monomers, 1 000 g of each prepolymer according to table 1were introduced to the stock reservoir vessel of a short-path evaporatorapparatus of the type VKL 70 from VTA Verfahrenstechnische Anlagen GmbHDeggendorf, which had a evaporator area of 0.04 m² and was set to athroughput of 0.1 to 2 l/h, and heated to 80° C. (prepolymer 1) or 60°C. (prepolymer 2). The evaporator and condenser were preheated to thetarget temperature given in table 2. Once stirring had commenced, thevacuum had been set and the intended flow rate had been attained, themonomer-containing prepolymer was fed from the stock reservoir vesselthrough the short-path evaporator; Prepolymers having a remainingmonomer content of smaller than 0.05% by weight were prepared by theprocess described. Furthermore, a monomer was recovered that had apurity of greater than 97%. The process of the invention for thepreparation of prepolymers provides an isocyanate monomer that can beused again for the preparation of prepolymers without an additionalprocessing step. TABLE 2 Prepolymer 1 Prepolymer 3 Distillationparameters Pressure [mbar]  0.03  0.02 Flow rate [l/h]  0.17  0.27Stirrer speed [rev/min] 415    410    Stock reservoir vessel temperature80   60   [° C.] evaporator temperature [° C.] 120    80   Condensertemperature [° C.] 50   20   NCO content [% by weight] Before short-pathdistillation 5.5 6.3 After short-path distillation 2.6 3.5 Isocyanatemonomer content**) [%] Before short-path distillation 7.6 6.5 Aftershort-path distillation  0.02  0.01 Viscosity of prepolymer at 25° C.[mPa · s] Before short-path distillation 10 261      2 560     Aftershort-path distillation 23 483      5 385     Color number [iodine]Before short-path distillation 0.1 0.1 After short-path distillation 0.20.1**)Determined by HPLC

In table 3, the monomer removal by means of a single evaporator and bymeans of an evaporator battery are compared. In example 1, theprepolymers 4 and 5 are prepared from 2,4-MDI and polyol 1. After thepreparation, prepolymer 4 had an NCO content of 5.3% by weight, aviscosity of 25° C. of 7887 mPa·s and a diisocyanate monomer content of6.8% by weight. After the preparation, prepolymer 5 had an NCO contentof 5.6% by weight, a viscosity of 6768 mPa·s at 25° C. and a content ofmonomer diisocyanate of 7.4% by weight. TABLE 3 Prepolymer 4 Prepolymer5 Distillation parameters Pressure [mbar] 0.01 0.5//0.07 Flow rate [l/h]160 160//60  Stirrer speed [rev/min] 410 410 Stock reservoir vesseltemperature 80 80 [° C.] Evaporator 1 temperature [° C.] 120 120Evaporator 2 temperature [° C.] — 120 Condenser 1 temperature [° C.] 5050 Condenser 2 temperature [° C.] — 50 NCO content [% by weight] Beforethe distillation 5.3 5.6 After evaporator unit 1 3.6 3.9 Afterevaporator unit 2 — 3.3 Isocyanate monomer content [% by weight] Beforedistillation 6.8 7.4 After evaporator unit 1 0.10 2.53 After evaporatorunit 2 — 0.03 Viscosity at 25° C. [mPa · s] Before distillation 78686768 After evaporator unit 1 12941 8188 After evaporator unit 2 — 11724Color number [iodine] Before distillation 9.0 2.4 After evaporator unit1 10.8 5.6 After evaporator unit 2 — 7.4

The prepolymer 5 was demonomerized in an evaporator battery having twoevaporator units connected in series:

-   -   evaporator unit 1: short-path evaporator    -   evaporator unit 2: short-path evaporator

Both short-path evaporators were of the same type. The use of anevaporator battery instead of a single evaporator unit achieved adistinct improvement in the monomer removal.

As a comparison, monomer separation was carried out by solventextraction and high-pressure extraction with supercritical carbondioxide.

COMPARATIVE EXAMPLE A

Demonomerization of prepolymers by extraction with n-hexane in aKutscher-Steudel extractor perforator

The results are recorded in table 4. TABLE 4 4,4′-MDI 2,4′-MDIPolyetheralcohol Polyol 1 NCO content [% by weight] Before extraction5.5 5.6 After extraction 3.0 3.3 MDI monomer content [%]**) Beforeextraction 7.3 7.6 After extraction 1.0 0.6 Viscosity of the prepolymerat 25° C. [mPa · s] Before extraction 7 947     6 366     Afterextraction 21 096      10 517      Color number [iodine] Beforeextraction 1.0 2.4 After extraction 8.8 14.0 **)determined by HPLC

The solvent extraction had the following disadvantages:

The extractive separation of high. MDI monomer contents required longextraction times, in which the MDI prepolymer was exposed to thermalstress. This was reflected in the increase in the color number.

The monomer content was appreciably above 0.1% by weight.

COMPARATIVE EXAMPLE B

Demonomerization of MDI prepolymers through high-pressure extraction bymeans of supercritical carbon dioxide

Parameters: Ratio of prepolymer to carbon dioxide 1:7 Temperature inextractor 63° C. Pressure in extractor 220 bar  Temperature in monomerseparator 60° C. Pressure in monomer separator 55 bar Temperature incarbon dioxide condenser 13° C. Pressure in carbon dioxide condenser 56bar

Comparison of the two processes: extraction with supercritical carbondioxide and short-path evaporator distillation

The prepolymers were prepared by the general method from 4,4′-MDI andpolyol 1. High-pressure extraction Short-path with supercritical carbonevaporator dioxide distillation NCO content [% by weight] Beforeoperation 5.4 5.5 After operation 2.7 2.9 MDI monomer content [%]**)Before operation 7.7 7.6 After operation  0.28  0.04 Viscosity ofprepolymer at 25° C. [mPa · s] Before operation 11 928      10 261     After operation 20 472      18 392      Color number [iodine] Beforeoperation 0.1 0.1 After operation 0.5 0.2**)determined by HPLC

Disadvantage of the extraction with supercritical carbon dioxide: Thesolubility of the carbon dioxide used as an extractant is up to 0.4% byweight in the MDI prepolymer and up to 0.1% by weight in the MDImonomer. This normally makes an additional step necessary for thedegasification of the product.

1. A process for the preparation of prepolymers containing isocyanateand urethane groups, comprising the steps of a) reacting2,4′-diphenylmethane diisocyanate or mixtures of 2,4′-diphenylmethanediisocyanate and 4,4′-diphenylmethane diisocyanate or mixtures of 2,4′-,2,2′- and 4,4′-diphenylmethane diisocyanate and polyphenylpolymethylenepolyisocyanates with a less than stoichiometric quantity of a polyetheralcohol, b) removing the monomeric diisocyanates by distilling thereaction product from step a) by means of a short-path evaporator.
 2. Aprocess as claimed in claim 1, wherein the distillation in step b) iscarried out in an evaporator battery comprising at least 2 evaporatorsconnected in series.
 3. A process as claimed in claim 1, wherein step b)is carried out at a pressure of from 10 to 10⁻³ mbar.
 4. A process asclaimed in claim 1, wherein the evaporator comprises a vaporizer and acondenser and step b) is carried out at a temperature in the vaporizerof from 50 to 210° C. and a temperature in the condenser of from 15 to55° C.
 5. Prepolymers containing isocyanate and urethane groups, made inaccordance with a process as claimed in any of claims 1 to
 4. 6.Prepolymers containing isocyanate and urethane groups as claimed inclaim 5, comprising monomeric diisocyanates at less than or equal to0.1% by weight, based on the weight of the prepolymer.
 7. Prepolymerscontaining isocyanate and urethane groups as claimed in claim 5,comprising monomeric diisocyanates at less than 0.05% by weight, basedon the weight of the prepolymer.
 8. and
 9. (Cancelled).
 10. A method ofpreparing polyurethanes comprising reacting the prepolymers of claim 5with an isocyanate-reactive component.
 11. A method of preparingmelt-applied adhesives, packaging films, coatings or sealants,comprising reacting the prepolymers of claim 5 with anisocyanate-reactive component.